Subacute combined degeneration of spinal cord is due to deficiency of -

<p> Vitamin B 12 Complex organometallic compound with a cobalt atom. Vitamin B12 cooperates with folate in the synthesis of DNA, so deficiency leads to megaloblastosis. Good sources are liver, kidney, meat , fish, eggs, milk and cheese. Liver is the main storage source. Deficiency:- Associated with megaloblastic anemia( pernicious anemia), demyelinating neurological lesions in spinal cord and infeility. The symptoms include paresthesia( numbness and tingling) of fingers and toes. In advanced stages, confusion, loss of memory and psychosis. Neurological symptoms of pernicious anemia are believed to be due to accumulation of methylmalonyl CoA that interferes in myelin sheath formation. {Reference: Park&;s textbook of community medicine 23 rd edition}